Monthly Archives: April 2017

I study Faculty of Information Technology at VUT in Brno and the main aim of my bachelor thesis is a research of developing the cross-platform desktop applications. The adult spends approximately 2.5 hours per day on desktop computers as shown by the statistics that took place between 2008 and 2015. While the time spent on mobile phones increases, the time spent on desktop computers is, on the other hand, not decreasing. In my opinion, this has a great potential in developing a single desktop application that can be run on all major operating systems. An application such as this that can be built via Electron framework.

Electron

It is an open-source framework that allows the creation of native desktop applications on Linux, Windows and macOS platforms with web technologies like JavaScript, HTML, and CSS. A combination of Chromium and Node.js makes this possible. The application that is created by Electron has all the benefits of a native desktop application, such as access to the file system or system notifications. It is recommended to use the npm package manager of Node.js while developing the application. With the npm, a developer can record the necessary modules during development into the package.json file, run the application itself, etc.

Processes

In the Electron application, there are two types of processes: the main process and the renderer process. Each one has its own unique role. The process that runs script specified in the package.json as the main one is called the main process. The main process runs renderer processes and takes care of communicating with the API of the operating system. It allows developing the application with OS’s native GUI. Each renderer process renders the content of one web page. The renderer process runs in isolation from other renderer processes.

Development basic application

To develop basic Electron application, it is necessary to create three files: firstly, package.json with information about the application. Secondly, JavaScript file which will be run as the first one and, lastly, HTML file for creating GUI of application (i.e. the web page). The folder-structure of basic application can look like:

app/
├── package.json
├── main.js
└── index.html

To run the application, you can download last Electron release from the web and copy app folder to the downloaded application as below and execute binary electron (electron.exe on Windows, etc.).

Folder-structure of Electron application on macOS

electron/Electron.app/Contents/Resources/
└── app/

Folder-structure of Electron application on Windows and Linux

electron/resources/
└── app/

Application distribution

After the application is developed, the developer can package the app folder into asar archive instead of distributing the app’s source code. In such a case, the app folder can be replaced, which includes the source code with app.asar package.

There are three options for distribution. The first one is to manually download all the latest versions of Electron for the necessary platforms and copy the application to the appropriate folder. Using the command line, a third-party tool Electron-packager creates also these packages. The second option, which includes creating install files, is to use the tools also from third parties: Electron-builder or Electron-windows-store.The last option, which includes distributing source code instead of package asar, is to use npm package manager.

The tool Electron-builder uses Electron-packager and creates the file needed to install the application. The format of the installer, that Electron-builder supports for Windows is NSIS. The most widely used packages for Linux are the deb, rpm, freebsd and apk. Similarly, for macOS there are dmg, pkg and mas. Electron-builder also supports automatic updates. If there are dependencies to the native operating system, compilation is required on this system. Otherwise, it is possible to compile application on a selected operating system or use some build server such as AppVeyor for Windows and Travis for Linux and macOS.

Other tool developed by Microsoft for compiling Electron applications into the .appx package is called Electron-windows-store. The tool is available from Microsoft PowerShell. Electron-windows-store can be used only in the operating system Windows 10 with Anniversary Update. Application format for windows store will be generated from the package of the Electron-packager tool. Requirements to compile application:

You must have a certificate that supports the application

The Windows 10 SDK

Node.js with a minimum version of 4.

The last option is to distribute only the source code and use the npm package manager to install dependencies and run the application. It is necessary to have all dependencies in the package.json file. Then, user just downloads the source code and executes these commands: